Vitamin C modified cathode interlayer for efficient opaque and semitransparent organic photovoltaics

Abstract

Minimizing the interfacial electrical losses is a key pathway for both opaque and semitransparent organic photovoltaics (STOPVs). Here, we propose a new method of using vitamin C (VC) to modulate the performance of the cathode interlayer (CIL) and thus optimize the electrical losses of device. Molecular dynamics simulation reveals that VC can improve the long-range packing order of CIL molecules, which is beneficial to charge transport. In addition, the CIL modulation strategy facilitates the establishment of a better contact between the active layer and the metal cathode and thus suppresses the charge carrier recombination. Comprehensive optimizations, including electrode thickness, donor:acceptor ratio and optical engineering, are further carried out to compromise the energy conversion and visible transmission for high-performance STOPVs. As a result, the opaque device exhibits a champion power conversion efficiency of 19.8%, and the best STOPVs shows a high light utilization efficiency of 4.53%, where the efficiency and the average visible transmission are 12.1% and 37.4%, respectively.